Electrically conductive bamboo charcoal@cellulose nanofibrils based composite membranes designed for electromagnetic interference shielding and flame retardant

Recently, developing multifunctional biochar based materials has been concerned by experts and scholars, but the weak electrical conductivity of biochar itself will limit its application. Targeting this issue, electrically conductive bamboo charcoal (EBC) was constructed for catalytic carbonization by mixing ferric chloride with bamboo charcoal, followed by mixing cellulose nanofibrils (CNF) as the skeleton and a small amount of multi-walled carbon nanotubes (MWCNT) as the conductive enhancer to constract a conductive EBC@CNF@MWCNT composite aerogel by freeze drying. Subsequently, the aerogel was soaked with polydimethylsiloxane (PDMS) and hot pressed into a membrane. In the system, EBC and MWCNT were distributed uniformly in the CNF skeleton to form three-dimensional conducting network, the obtained conductive E @ CNF@M@PDMS composite membrane displayed excellent conductivity (47 S/m) and remarkable EMI shielding performance (39.5 dB, absorption loss of about 75%), as well as good flame retardant ability (LOI of 27.6%) and hydrophobicity (115.4°). Based on its outstanding properties and simple preparation, it is considered to provide a new strategy for developement of environmentally friendly multifunctional biochar based materials.